In a typical prior art magnetic disk recording system a slider containing magnetic transducers for reading and writing magnetic transitions flies above the disk while it is being rotated by a spindle motor. The disk includes a plurality of thin films and at least one ferromagnetic thin film in which the recording (write) head records the magnetic transitions in which information is encoded. The magnetic domains in the media on can be written longitudinally or perpendicularly. Perpendicular magnetic recording is considered to be superior to longitudinal magnetic recording for ultra-high density magnetic recording. The increase demand for higher areal density has correspondingly led to increase demand to explore ways to reduce the width of the write pole piece, increase the write field strength, and improve the write field gradient.
In a disk drive using perpendicular recording the recording head is designed to direct magnetic flux through the recording layer in a direction which is generally perpendicular to the plane of the disk. Typically the disk for perpendicular recording has a hard magnetic recording layer and a magnetically soft underlayer. During recording operations using a single-pole type head, magnetic flux is directed from the main pole of the recording head perpendicularly through the hard magnetic recording layer, then into the plane of the soft underlayer and back to the return pole in the recording head. The area of the main pole piece facing the air-bearing surface is designed to be much smaller than the area of the return pole piece. The shape and size of the main pole and any shields are the primary factors in determining the track width. FIG. 1(A) illustrates a prior art disk drive 10 with a head 20 for reading and writing transitions on the associated disk 16 which comprises the thin films of the magnetic recording media 17 which are deposited on substrate 18. The write head is inductive and includes a coil 31 and pole pieces P1 and P2. The section taken is perpendicular to the air-bearing surface. The read and write elements of the head (also called a slider) are built-up in layers on a wafer using thin film processing techniques to form a large number of heads at the same time. Conventionally after the basic structures for the heads have been formed the individual heads (original) rows of heads are cut from the wafer to expose what will become the air-bearing surface after further processing. The processing of the air-bearing surface typically includes lapping and formation of air-bearing features typically called rails. The air-bearing features separate the active components of the head from the air-bearing surface which is further separated from the media by an air gap.
Conventionally the coil 31 for the inductive write head is fabricated from copper and then encapsulated in hard bake photoresist which requires baking at a temperature of 230 degrees C. or more. This temperature limits the materials and designs that can be used for the magnetic sensor. The hardbake material also has a thermal expansion characteristic which is a poor match for the other materials in the head. In addition, for high aspect ratio coils, where the height of the coil is several times the spacing (pitch) between the coil turns other fill techniques such as sputtering can result in undesirable voids between the coil turns. FIG. 1(B) illustrates such a problem where coil 31 and pole piece 35 have been patterned. Sputtered material 34 applied to the relatively deep, narrow trenches between the coil turns can result in “pinch-off” areas 36 where the sidewall deposition grows together near the top of the trench before the bottom of the trench has been filled resulting in voids.
In US patent application 20030204952 by Crue, et al. a recording head is described with inorganic, electrically insulating materials within the recording head. The insulating materials are vacuum deposited, with no need to use a hard bake process that would be required for use of organic insulators. In one embodiment, the write gap is first masked, and then the coil is deposited on the write gap. A slightly larger area is then exposed within the mask, permitting insulation to be deposited over the coil. In a second embodiment, the coil and associated insulation are deposited and then milled to have a tapered configuration.